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標題: | 以二維模擬分析鈣鈦礦太陽能電池之遲滯效應和優化條件 Analysis of the Hysteresis Effect and Optimization of the Efficiency for MAPbI3-based Perovskite Solar Cells with Two Dimension Simulation |
作者: | En-Wen Chang 張恩文 |
指導教授: | 吳育任(Yuh-Renn Wu) |
關鍵字: | 鈣鈦礦太陽能電池,離子遷移,電流-電壓遲滯,表面紋理結構,表面電漿共振, perovskite solar cell,ion migration,current-voltage hysteresis,textured structure,surface plasmon resonance, |
出版年 : | 2020 |
學位: | 碩士 |
摘要: | 隨著全球暖化變得更加嚴重,世界正處於能源轉型的關鍵時期,各國皆積極尋求可替代的再生能源。其中由於鈣鈦礦材料優異的光電性能,新型有機無機雜化鹵化物鈣鈦礦太陽能電池(PSC)成為下一代太陽能電池的新秀,其效率在過去的十年中已從 3 %顯著提高到 23.3 %,是國際學術研究中的熱門議題,同時也具有巨大的商業化潛力。然而鈣鈦礦光電元件的遲滯效應一直是尚未解決的問題,它不但會影響測量的準確性和功率轉換效率的可信度,同時也跟有機光電元件不穩定性有很大的關聯。因此,我們實驗室開發了不同的模擬軟體,藉以分析鈣鈦礦太陽能電池中遲滯效應的物理機制。而通常提升元件表現和載流子擴散長度需要投入大量的研究成本和時間,因此,本論文也積極研究在不需要改善材料品質的前提下,針對穩定性好與差的鈣鈦礦光電元件提出優化效率的方法。 在本論文中,首先用二維時域有限差分法(2D-FDTD)構建了一個光學模型,計算太陽光源入射的光場分布以及光生載子分布。接著藉由二維泊松方程式(Poisson`s equation)和漂移擴散方程組(drift-diffusion equation)來模擬有機材料和非有機材料的電性特性,並計算鈣鈦礦太陽能電池中載流子的分佈,以及電流密度-電壓曲線和能帶圖等。此外我們根據實驗理論,利用二維泊松和漂移擴散方程組架構隨時間變化的離子漂移-擴散模型,用以研究由離子遷移作用引起的鈣鈦礦太陽能電池的遲滯特性,並在不同條件下進行了建模,發現與元件的遲滯特性具有很大的相關性,它取決於(1)外加偏壓的掃描 速率; (2)MAPbI3 材料中的離子濃度,以及(3)MAPbI3 的載子壽命。還分析了傳統正式(n-i-p)和反式(p-i-n)MAPbI3 結構太陽能電池的遲滯表現,結果顯示傳統架構的 PSC 具有較大的遲滯效應,我們推斷傳統結構和倒置結構的差異在於器件內部內建電壓差所導致,該差異導致碘離子(I-)遷移至傳輸層並影響載子傳輸與提取,進而導致不同的遲滯現象。此外,本論文的目的是針對不同載子壽命的 PSC 提升元件的效率,分別是 1奈秒、10 奈秒、1000 奈秒的 MAPI3 太陽能電池,並在 FTO 基板上方設計 了三角凹槽的週期性的紋理表面,利用波動光學的方式捕捉太陽光,以增加光電流。並調整了三角結構的振幅和周期以及材料厚度,以找到不同載子壽命的最佳效率優化的週期性紋理結構。通過將 FTO 的厚度從 250nm 減小到50nm,將 Spiro-OMeTAD 的厚度減小到 40nm 至 100nm,可以極大地增加MAPbI3 的光電流並改善 PCE。 因此,在具有適當的三角形結構和材料厚度的情況下,載流子無輻射壽命為 1 奈秒的元件效率從 11.48%提高到 15.34%,載流子無輻射壽命為 10 奈秒的元件效率從 14.02%提高到 18.03% ,載流子非輻射壽命為 1000 奈秒的元件效率從 18.01%提高到 22.68%。 As the global warming has become more serious, the world is in a critical era of energy transformation to the sustainable energy. Among that, perovskite solar cell (PSC) is the subject of international research, attributed to the excellent photoelectric performance of novel organic-inorganic hybrid halide perovskite materials. However, there has been an issue of hysteresis effect of PSC, which affects the accuracy and credibility of the power conversion efficiency (PCE) of device. The hysteresis characteristic is also dependent on the stability of organic perovskite material. Thus, our laboratory is dedicated to the simulation for the organic and non-organic hybrid perovskite photovoltaic devices to analyze the physical mechanism of hysteresis effect. In this essay, the two-dimensional simulation of PSCs is modeled. For the light field simulation, two-dimensional finite-difference time-domain (2D-FDTD) method is applied to obtain the distribution of photo-generated carriers. Poisson’s and drift-diffusion equations are used to calculated the transmission of carriers in PSC. The hysteresis characteristics of PSCs caused by ion migration is investigated by the time dependent ion model based on the two-dimensional Poisson and drift-diffusion equations under different conditions. The I-V hysteresis characteristics of PSCs is depending on (1) bias scan rate; (2) concentration of ion in MAPbI3 material, and (3) carrier lifetime of MAPbI3.The hysteresis effect of the traditional and inverted architecture MAPbI3–based solar cells is analyzed, and the results show that traditional architecture PSCs have larger hysteresis effect. It is due to the difference of built-in voltage of the device, which induces (I- ) ion migration to the transport layer and affect the depletion field. In addition, this essay aims at improving the efficiency of PSC with different carrier nonradiative lifetimes of MAPI3. A periodic textured surface with triangular grooves is designed above the FTO substrate to capture sunlight by the methods based on wave optics to increase photocurrent. The amplitude and period of structure and thickness of MAPbI3 are adjusted to find the optimal periodic textured structure of PSC. Additionally, by reducing the thickness of FTO from 250nm to 50nm and the thickness of Spiro-OMeTAD ranged from 40nm to 100nm, the photocurrent of MAPbI3 is greatly increased and PCE is improved. Therefore, the efficiency of the PSC with a carrier non-radiation lifetime of 1 ns is further improved from 11.48% to 15.34%, and the efficiency of the PSC with a carrier non-radiation lifetime of 10 ns increases from 14.02% to 18.03%, and the efficiency of a PSC with a carrier nonradiative lifetime of 1000 ns is increased from 18.01% to 22.68%. |
URI: | http://tdr.lib.ntu.edu.tw/jspui/handle/123456789/69082 |
DOI: | 10.6342/NTU202003635 |
全文授權: | 有償授權 |
顯示於系所單位: | 光電工程學研究所 |
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